Long-term outcomes and prognostic factors in juvenile dermatomyositis: A systematic review of studies with more than 12 months of follow-up

BACKGROUND: Juvenile dermatomyositis (JDM) is a rare autoimmune myopathy in children and young people (CYP), with long-term outcomes that remain poorly defined. We systematically reviewed long-term studies to summarise outcomes and prognostic factors associated with remission or persistent disease. METHODS: This review was registered in PROSPERO (ID 1085849). A PubMed search (November 2025) identified eligible studies based on predefined PICO criteria. Inclusion required >10 CYP with JDM, ≥12 months follow-up, outcome reporting, and English full text. Studies with mixed cohorts or < 12 months follow-up were excluded. Data were independently extracted by two assessors, and study quality was evaluated using the Newcastle-Ottawa Scale. RESULTS: Of 341 records screened, 42 studies (2000-2025) including 6194 CYP met criteria. Study quality ranged 4-9/9, with 38.1% rated high quality. Most were retrospective or prospective cohorts. Follow-up ranged 1-21.7 years - only 8 studies had >10 years follow-up. Nine studies using PRINTO remission criteria reported remission rates of 21.6-73.0%, with pre-PRINTO studies showing monocyclic remission rates of 24.5-70.3%. PROM-based analyses identified persistent disease in 11-12% of cases, and one study found 59% patient-reported active disease at 12 years. The most frequent complication was calcinosis (10-40%). Mortality occurred mainly in the acute phase due to pulmonary or infectious complications. Poorer outcomes were associated with younger onset, African ancestry, socioeconomic disadvantage, diagnostic delay, and high baseline skin and muscle involvement. CONCLUSION: Long-term follow-up data in JDM remain limited, but remission is achievable. Early diagnosis, timely treatment, and validated outcome measures are for improving prognosis.